It is known that pieces, such as cylindrical paper rolls, are wrapped by using wrapping apparatuses, known as such, which perform the wrapping by means of a wrapping film, preferably a transparent stretch film. One known wrapping apparatus is presented in patent publication U.S. Pat. No. 5,086,610. These wrapping apparatuses normally use a thin plastic film which is guided around the piece while the piece is rotated around its central line. When the wrapping film which is narrower than the piece is fed around the piece in the longitudinal direction of the piece, i.e. in the direction of the central line, it is also known to transfer the wrapping apparatus in the direction of the central line to wrap the whole envelope surface of the piece with several layers of the wrapping film. At the final stage of the wrapping, the film is cut and the end of the film can be welded on to other films by hot sealing. As to the techniques involved in cutting, sealing and feeding of the film, reference is made e.g. to patent publication U.S. Pat. No. 5,092,109. During the wrapping, the wrapping film is also stretched in a controlled way, as presented e.g. in patent publication U.S. Pat. No. 5,054,263 which is referred to in this respect.
After the wrapping, the pieces are also normally supplemented with a sheet-like label which comprises e.g. information about the material of the piece, identification codes, addresses, production data, text, figures, instructions, warnings, etc. In a known way, the label, or alternatively several labels, are attached on the outer surface of the outermost wrapping film layer on the wrapped piece, e.g. by manually pasting. Also, there are different known apparatuses which automatically add the required adhesive, such as hot-setting adhesive, on one surface of the label and transfer the label e.g. by pressing with feeding rolls onto the surface of a stationary piece. In the case of larger pieces, such as rolls of newsprint or magazine printing paper, the labels can be placed in position by a robot or a manipulator equipped with a gripping device operating on the suction principle. Furthermore, it is possible that the label is attached to the surface of the stopped piece before starting the wrapping.
However, a considerable drawback in the prior art presented above is the fact that the act of securing the adherence of the label during the different steps of transportation and manipulation of the piece sets considerable demands on e.g. the properties and endurance of the adhesive under various exposure conditions, the technical way of adhesion as well as the accuracy of the fixing. Moreover, varying ambient conditions can directly affect the label adhered onto the outer surface of the wrapped piece, involving the risk that the information may disappear at least partly if the label is not e.g. coated. A label placed onto the surface of the piece before the wrapping is difficult to read e.g. by a machine under several layers of wrapping film, particularly if the bar code of the label must be interpreted reliably, if the wrapping film is coloured, or if creases are formed on several film layers on the label.
Due to the facts presented above, pasting and fixing apparatuses of prior art for fixing a label become complex and expensive. Also, the materials for durable labels of special make may require distinct fixing methods specific to them. However, the piece itself or the wrapping film layers must not be damaged in connection with the fixing.